doi:10.1038/nindia.2014.8 Published online 21 January 2014
Researchers have synthesized a drug-releasing polymer gel consisting of chitosan nanoparticles distributed in sodium alginate gel. It can be used to release dorzolamide hydrochloride, a drug used for treating eye disorders such as glaucoma1 .
Glaucoma is an age-related disease that increases the fluid pressure in the eye, resulting in progressive loss of visual field. If untreated, glaucoma can lead to vision loss. Drugs currently used for treating glaucoma have drawbacks such as poor bioavailability in the eye.
To develop an efficient drug-delivery system for glaucoma, the researchers synthesized three drug carriers: chitosan nanoparticles alone, sodium alginate gel alone and chitosan nanoparticles dispersed in sodium alginate gel. They then loaded these three drug carriers with dorzolamide hydrochloride and tested their ability to release the drug in a culture medium and in the eyes of male rabbits.
The nanoparticles and sodium alginate gel drug carriers released about 74% and 70% of drug respectively in 8 hours. The drug carrier consisting of chitosan nanoparticles in alginate gel released 58% of drug in 8 hours; this gradual sustained release makes it a better drug carrier than chitosan alone and alginate gel alone.
One of the key qualities of a good drug carrier is a good mucoadhesive strength. Of the drug carriers, the chitosan nanoparticles in alginate gel exhibited the highest mucoadhesion due to the cumulative effect of the chitosan particles and alginate.
In animal studies, the drug carrier containing chitosan nanoparticles in alginate gel permeated the anterior and posterior chambers of the eyes, resulting in high bioavailability of the drug. In addition, this drug carrier is a non-irritant, making it a suitable candidate for treating glaucoma.